How severe is CVE-2021-24031?

CVE-2021-24031 has a CVSS 3.x base score of 5.5, rated medium severity. It is exploitable over local access with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity none, and availability none.

Is CVE-2021-24031 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (35th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-24031?

CVE-2021-24031 affects Facebook Zstandard. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-24031?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2021-24031 published?

CVE-2021-24031 was published on 2021-03-04 and last updated on 2026-06-17.

CVE-2021-24031

CVE-2021-24031 is a medium-severity vulnerability in Facebook Zstandard with a CVSS 3.x base score of 5.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-276.

Key facts

Severity: Medium (CVSS 3.x base score 5.5)
CVSS v2: 2.1
EPSS exploit prediction: 0% (35th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-276
Affected product: Facebook Zstandard
Published: 2021-03-04
Last modified: 2026-06-17

Description

In the Zstandard command-line utility prior to v1.4.1, output files were created with default permissions. Correct file permissions (matching the input) would only be set at completion time. Output files could therefore be readable or writable to unintended parties.

Frequently asked questions

What is CVE-2021-24031?: In the Zstandard command-line utility prior to v1.4.1, output files were created with default permissions. Correct file permissions (matching the input) would only be set at completion time. Output files could therefore be readable or writable to unintended parties.
How severe is CVE-2021-24031?: CVE-2021-24031 has a CVSS 3.x base score of 5.5, rated medium severity. It is exploitable over local access with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity none, and availability none.
Is CVE-2021-24031 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (35th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-24031?: CVE-2021-24031 affects Facebook Zstandard. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-24031?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2021-24031 published?: CVE-2021-24031 was published on 2021-03-04 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:facebook:zstandard:*:*:*:*:*:*:*:*

More vulnerabilities in Facebook Zstandard

CVE-2019-11922 — High (CVSS 8.1): A race condition in the one-pass compression functions of Zstandard prior to version 1.3.8 could allow an attacker to…
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CVE-2021-24032 — Medium (CVSS 4.7): Beginning in v1.4.1 and prior to v1.4.9, due to an incomplete fix for CVE-2021-24031, the Zstandard command-line…

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